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PostPosted: Wed May 24, 2017 10:29 am 
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848cc
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Location: NSW/ACT
Thinking of going for straight cuts when I rebuild the gbox. I know its loud. I know its noisy. car is probably gonna be used just on weekends. sometimes to work (only 5km away anyway) and the occassional trackday.

am I really gonna hate life with how loud they are?

I'm not gonna be doing hard core racing so in that sense the normal gears would be fine but ya know. race car noises etc.

and are they more of a pain in the butt to use? I dont think they're harder to engage and all that jazz yeah?


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PostPosted: Wed May 24, 2017 10:41 am 
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Location: Wodonga - Vic/NSW border
my friend has just put a box with straight cut gears in his motorkhana car - he's a worrier at the best of times and I was expecting him to hate it, but he loves it, he says gearchanges are really nice. I haven't driven it yet...

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PostPosted: Wed May 24, 2017 10:43 am 
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1275cc
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Location: Wollongong, NSW
If you just want the noise you can get some straight cut drop gears rather than the full gear set. E.g.
http://www.med-engineering.co.uk/produc ... et-std-pin

I can appreciate the noise coming from other people's cars but it's not for my car!

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PostPosted: Wed May 24, 2017 11:05 am 
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848cc
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Location: NSW/ACT
is drop gear = lay gear?


also what ratios should I look into? currently only have the 998 in there which I might slap it onto (but would I be able to re use the same stuff on the 1275? as in just remove box from this and put it into a different motor?)

I just want a slightly longer one so that when i'm at 100 I'm not at 4k rpm.


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PostPosted: Wed May 24, 2017 11:14 am 
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1275cc
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Drop gears are:
Primary gear (top - on the crank)
Idler gear (in the middle)
Input gear (bottom - on the input/first motion shaft)


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PostPosted: Wed May 24, 2017 11:17 am 
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848cc
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ahhh righto. Yeah I was told I could just use that and get the same noise. Might be a cheaper venture to just change drops and rebuild the standard ones. maybe just needs synchro haha.

Whats the best option to look into (that wont break my bank) to get a higher cruising speed at a lower RPM?


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PostPosted: Wed May 24, 2017 11:20 am 
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998cc
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Garagedefend wrote:
ahhh righto. Yeah I was told I could just use that and get the same noise. Might be a cheaper venture to just change drops and rebuild the standard ones. maybe just needs synchro haha.

Whats the best option to look into (that wont break my bank) to get a higher cruising speed at a lower RPM?



Wouldn't that be just the final drive in the diff???

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PostPosted: Wed May 24, 2017 11:33 am 
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848cc
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yeah I'm thinking thats the easiest bet. Are there aftermarket options though or do I just have to wait to find a used longer ratio one? although I've only checked oz.minispor they seem to only have same ratio alternatives to standard


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PostPosted: Wed May 24, 2017 11:38 am 
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1275cc
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Stock on 850 and early 998 is 3.76:1 final drive. A 3.44 out of a Cooper S or Clubby would be better, you can go lower (3.1, 2.9 etc) but this will affect the acceleration. Should be plenty of used 3.44 sets around (pinion gear and crownwheel)

You can also change the final drive ratio slightly using different ratio drop gears.

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PostPosted: Wed May 24, 2017 11:46 am 
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848cc
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If you use the straight cut drop gears you have the option of an overdrive set which would suit both your goals of noise and lower RPM per MPH. If you are going to use the 998 the gear set is different and if you go to a 1275 you will need to buy a new primary gear to suit the bigger crank tail.

And S/C drops are NOISY more so than the gearbox S/C set

Also at your goal of 100MPH you WILL be using more than 4,000 RPM with any gear set that you could use on the road without abusing the clutch on an everyday basis.


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PostPosted: Wed May 24, 2017 1:24 pm 
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minimans wrote:
Also at your goal of 100MPH you WILL be using more than 4,000 RPM with any gear set that you could use on the road without abusing the clutch on an everyday basis.


I reckon he meant 100kph... :wink:

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PostPosted: Wed May 24, 2017 1:55 pm 
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100mph even with a 3.44 diff is around 6,000rpm :roll:

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PostPosted: Wed May 24, 2017 2:27 pm 
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848cc
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I wont be going to 1275 right away so I suppose I can do the 998 and just change the bits over in the future. I think my old deluxe w a 1275 had a 3.1. Acceleration was a bit slow but it would cruise nicely at 110 and I remember winding it out to about 130 when overtaking. so I dont mind something like taht (although like you said its not as peppy) so maybe a clubman one would work. just cause form my house to get to mechanics etc and all that I always have to get on a highway and sit at 100kph for about 20/30 kms. so a little more speed with a little less revs would be nice.

So for now, to start at least, maybe I'll just fit SC drops. Its not like I'll be shifting in anger. the 998 wouldnt be up to it anyway haha. it has a slight grind in 3rd and 4th but I can shift it so that it doesnt.

is there any local or cheaper alternative to the MED drops? and when I install them, does the box have to come apart enough that I may as well look into why 3rd and 4th grind or is it accessible enough to just to the drops first?


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PostPosted: Wed May 24, 2017 6:05 pm 
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998cc
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Joined: Tue Sep 06, 2005 1:26 pm
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I used an ST sc/cr 3 synchro gearset that I got from the Uk in 1972 in my daily drive road car for more than 10 years in both Melbourne and Adelaide traffic and frequent interstate blasts to Sydney and Canberra. With a 45 Weber, four blade fan and big bore Brownrigg exhaust it was loud but lovely sounding. The gears were not that noisy and tended to be drowned out by the Weber. Maybe sc drop gears would have been a different matter, I don't know. Gear changes were super slick, often without ever having to use the clutch.

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PostPosted: Wed May 24, 2017 8:11 pm 
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Garagedefend wrote:
when I install them, does the box have to come apart enough that I may as well look into why 3rd and 4th grind or is it accessible enough to just to the drops first?


you don't need to separate the gearbox from the engine, so no

but it's not a lot of extra work to split it and rebuild the 'box anyway

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